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RoxyCoding

Roxy Blender MCP

by RoxyCoding
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Python
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create_primitive

Create a 3D primitive at its true size with real mesh dimensions and scale 1, so bevels stay even. Returns its world bounding box so you can place the next part precisely.

Instructions

Create a primitive built at its TRUE size (mesh data, scale stays 1, so bevels stay even). Returns its world bounding box so you can place the next part precisely.

Input Schema

TableJSON Schema
NameRequiredDescriptionDefault
nameNo
sizeNobox: [x,y,z] metres (or one number for a cube). plane/grid: [x,y].
typeYesquad_sphere = all-quad sphere, best with subdivision. tube = hollow cylinder (radius + inner_radius). capsule = cylinder with hemispherical ends (depth = total length).
bevelNoRounded edges via an angle-limited Bevel modifier with hardened normals: width in metres (e.g. 0.002 for a 10 cm part), or {width, segments, angle}. true = automatic width.
depthNoHeight along Z for cylinder/cone/tube/capsule/pyramid.
ringsNosphere: rings; torus: minor segments; cylinder/cone: height segments (needed before bend/twist).
originNoWhere the origin sits on the part's bounding box: center, bottom, top, left, right, front, back, min, max, or keep (geometry coordinates exactly as given). origin='bottom' + location z=0 stands a part on the floor.center
parentNoParent object name (world transform kept).
radiusNocylinder/cone/tube/sphere/capsule radius; torus major radius; pyramid corner radius.
shadingNoauto = smooth with sharp edges kept above smooth_angle (best default); smooth; flat.auto
locationNoWorld position [x,y,z] (metres) of the object origin.
materialNoMaterial preset name (list_material_presets), or {preset, color, roughness, weathering, ...} like apply_material, or the name of an existing material. Presets with a real-world scan use Poly Haven automatically; {'polyhaven': 'mossy rock'} picks any Poly Haven texture by description.
rotationNoRotation [x,y,z] in degrees.
segmentsNoRadial resolution (default 48; quad_sphere: per cube edge, default 8; grid: cuts).
collectionNoCollection to put it in (created if missing).
radius_topNocone/cylinder top radius (0 = point).
subdivisionNoSubdivision Surface levels (1-3) for soft/organic shapes.
inner_radiusNotube inner radius.
minor_radiusNotorus tube radius.

Schema Changelog

Changes observed during successful MCP inspections.

  1. First observedv0.2.0

TDQS

A3.5/5.0
Behavior3/5

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations, the description carries the full behavioral burden. It usefully discloses a non-obvious trait (mesh data with scale held at 1 so bevels stay even) and the return value (world bounding box), but does not cover selection state, creation side effects, or permissions, leaving meaningful behavioral gaps.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Conciseness5/5

Is the description appropriately sized, front-loaded, and free of redundancy?

Two tight sentences, zero filler, with the key trait (TRUE size / scale 1) and the return value front-loaded before any elaboration. Every clause earns its place.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Completeness3/5

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a 19-param, no-annotation, no-output-schema tool, the description covers the return value (compensating for the missing output schema) and the scale behavior, but omits routing to the other creation tools and any side-effect/permission context. Complete enough to call, incomplete as guidance.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Parameters3/5

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 95%, so the schema already documents all 19 parameters in detail. The description adds essentially no parameter syntax beyond the passing mention of bevels, so the baseline 3 is appropriate when the schema does the heavy lifting.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Purpose4/5

Does the description clearly state what the tool does and how it differs from similar tools?

The description states a specific verb and resource ("Create a primitive") and adds a distinguishing trait (built at TRUE size, scale stays 1). It does not differentiate from the numerous sibling creation tools (create_lathe, create_extrusion, create_sweep, create_loft, create_pipe), so an agent cannot tell from the text alone when a primitive beats a lathe or extrusion.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Usage Guidelines3/5

Does the description explain when to use this tool, when not to, or what alternatives exist?

Usage is only implied: "so you can place the next part precisely" hints at an iterative placement workflow, but there is no explicit when-to-use, when-not-to-use, or named alternative among the many create_* siblings. Adequate but gapped.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.

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